1. Field of the Invention
The invention relates to a worm-driven hose clamp comprising a clamping strip, a housing, and a clamping screw comprising a head and a threaded shaft, wherein the clamping strip comprises overlapping end portions. The radially outwardly positioned one of the end portions is provided with thread elements which interact with the threaded shaft, and the radially inner end portion is positive-lockingly connected with the bottom of a housing surrounding the end portions and the threaded shaft of the clamping screw. The housing supports the clamping screw in both circumferential directions of the hose clamp. The housing is comprised of a housing band whose ends delimit an open butt joint in the area of the housing bottom and are connected to one another by interlocking undercuts of their edges defining the open butt joint. The bottom of the housing comprises at least on the transverse edge facing away from the head of the clamping screw, a radially outwardly angled tongue on both sides of the open butt joint. The tongue penetrates through an opening in the radially inwardly positioned end portion of the clamping strip.
2. Description of the Related Art
In a known worm-driven hose clamp of this kind (DE 196 33 435 C1) a single opening is formed at each transverse edge of the housing bottom in the form of a groove which is pressed radially outwardly and extends transverse to the strip. On each transverse edge the two tongues engage together the same opening wherein the tongues are positioned so as to laterally rest against one another. The tongues are provided to prevent spreading of the open butt joint from a central area, where the edges of the open butt joint are connected by positive-locking engagement of interlocking undercuts, toward the transverse edges of the housing bottom, in particular, in a direction toward the transverse edge positioned at the end where the head of the clamping screw is located.
This type of connection of the abutting ends of the housing band is able to withstand very high clamping forces. However, for even higher clamping forces there is the risk of deformation, in particular, of the area of the clamping strip opening positioned on the transverse edge of the housing bottom facing away from the head of the clamping screw, and there is still the risk of spreading of the open butt joint, particularly at the side of the screw head.
For a worm-driven hose clamp of the aforementioned kind, it is an object of the present invention to reduce the risk of deformation of the clamping strip and to configure the connection of the ends of the housing band in the area of the housing bottom so as to be even more stable.
In accordance with the present invention, this is achieved in that the tongues are oriented in the circumferential direction of the clamping strip and in that each tongue has correlated therewith its own opening having positioned adjacent thereto a radially inwardly pressed depression oriented away from the respective bottom edge in the circumferential direction of the clamping strip, wherein each depression is matchingly engaged by a tongue, respectively.
In this solution, at each transverse edge of the housing bottom there are two areas of radially free end faces of the neighboring depressions resting against the sides of each tongue and providing support surfaces, i.e., a total of four areas or support surfaces is provided at each transverse edge. These areas are subjected to a reduced surface pressure in comparison to only two areas provided on each transverse edge, as is the case in the known embodiment. Moreover, the spreading of the open butt joint on the housing bottom by the lateral deflection of the radially outer end portions of the clamping strip is prevented, in particular, on the side of the head of the clamping screw, up to even high clamping force since each tongue rests against a respective sidewall of the depression when one sidewall of the housing is loaded laterally (axially) in the direction of spreading of the open butt joint as a result of a force of the radially outer end portion of the clamping strip acting in the axial direction of the clamp. In the past, only one of the two adjacently positioned tongues was supported on the edge of the single opening receiving both tongues.
Preferably, it is ensured that the tongues are pressed away from the underside of the housing bottom radially outwardly. In this configuration, a stepped arrangement results at the transition from the housing bottom to the tongues. In this connection, the housing bottom can be supported underneath the tongues on the radially free end faces of the depressions in the circumferential direction of the hose clamp.
Moreover, it is beneficial when the housing bottom has on both sides of the open butt joint projections projecting past the inner side of the housing bottom which project into the openings positioned closest to the clamping screw head. These projections take up additional spreading forces and therefore also contribute to the stability of the housing bottom.
The projections can be formed by tabs formed between the legs of U-shaped cuts in the bottom and pressed out of the bottom plane. The tabs rest with their free ends against those edges of the openings positioned farthest away from the open butt joint, respectively. These tabs can receive especially high forces and can be formed in a simple way.
Moreover, it can be provided that the housing is provided only on its right side, which is defined when the clamping screw is positioned above the clamping strip and viewed from the head in the direction toward the threaded shaft of the clamping screw, with a lateral stabilizer portion whose wall comprises, in an area radially external to the radially outer end portion of the clamping strip adjacent to the free end of the clamping screw shaft, a wall portion extending from the rounded top of the housing tangentially to a radial wall portion of the lateral stabilizer portion and further comprises, adjacent to a central portion of the threaded shaft of the clamping screw, a curved wall portion resting against the threaded shaft and an axial wall portion connecting the curved wall portion with the radial wall portion. This lateral stabilizer portion prevents a lateral tilting of the housing in the rotational direction of the clamping screw. Its curved wall portion contributes to the guiding action of the clamping screw tangentially to the hose clamp. The slanted wall portion prevents widening of the curved wall portion and of the axial wall portion during clamping. At the same time, the slanted wall portion reduces the contact surface between the thread of the threaded shaft of the clamping screw and the wall of the housing so that the thread in the area of the slanted wall portion experiences reduced wear. The clamping screw can thus be rotated easily even after several actuations or rotations. Accordingly, the torque required for clamping the clamping screw remains minimal even for an extended service life.
The curved wall portion and the axial wall portion can be formed by pressing the sidewall of the housing inwardly so that a wall portion extending transversely to the clamping screw is formed between the slanted wall portion, the curved wall portion, and the axial wall portion. This imparts high stiffness to the sidewall of the lateral stabilizer portion against spreading.
Preferably, the plane of the transversely extending wall portion intercepts approximately the center of the section of the clamping screw engaging the clamping strip with its thread. In the area of the center of the section of the clamping screw engaging the clamping strip with its thread, the housing is subjected to especially high forces which have the tendency to widen the housing. In the described position, the transversely extending wall portion counters such a tendency for widening in a particularly beneficial way.
The corners of the housing end facing away from the head of the clamping screw are preferably rounded. This reduces the risk that the these corners will penetrate the material of an end section of a hose to be clamped onto a socket or pipe section and will thus damage the hose.
The radially outer corners of the free end of the tongues can be beveled. With such a configuration, they will not impair, as would be the case with right angle corners, the movement of the radially outer end of the clamping strip relative to the radially inner end.
Moreover, it is advantageous when the lower edge of the depressions are substantially aligned with the underside of the housing bottom and the depth of the depressions decreases continuously to zero from the end adjoining the opening, respectively, to the opposite end. In this embodiment, a substantially continuous edge-free transition between the housing bottom and the inner side of the clamping strip is provided with a correspondingly uniform radial pressing of a hose onto the circumference of a socket or pipe.